The container industry has been various approaches to the solution of its requirement, particularly for food and like product containment, of impregnability of containers as respects pressure and vacuum. Applicants herein have participated in such efforts to meet the given requirement, as elicited in a U.S. patent discussed below and disclosing structure involving cap or closure refinement and container neck outlines cooperative with same.
Where one addresses the pressure and vacuum impregnability requirement with a view to accomodate standard container neck outlines, as contrasted with the above-noted involvement of applicants with specially configured container necks, the solution has typically involved the production of a cap, the separate production of a liner having the required sealing capabilities and a further step of assembling the individually produced cap and liner.
Other efforts have looked toward the common molding of a cap with liner, i.e., by introducing a common material into a mold configured to yield the composite cap and liner. This practice limits the composite product to uniform characteristics, e.g., resilience and like physical properties, since such material constitutes both the cap and liner. Thus, while the costly manufacturing step of assembling a separately made liner with a separately made cap is eliminated, performance limitations accompany the practice.